The literature discloses many ways of providing active ingredients in an encapsulated form. The encapsulation of active ingredients has various objectives, the main being, on the one hand, to protect labile or volatile ingredients from a degradation or any adverse interaction with an external element, and on the other hand to control the release of the encapsulated active ingredient and provide an efficient release only when desired, depending on the application.
Encapsulation methods and encapsulating matrix compositions are parameters which can be varied and are chosen as a function of the purpose for which a delivery system is designed. They are the object of many patents or patent applications.
Regarding encapsulation methods, extrusion has been widely described in the prior art, particularly in the patent literature. This method typically relies on the use of carbohydrate matrix materials which are heated to a molten state and combined with an active ingredient, before extruding and quenching the extruded mass to form a glass which protects said ingredient. Typical products issued from this method and used in the flavor industry are dry, granular delivery systems in which the active ingredient is a flavor uniformly distributed as droplets throughout a carbohydrate glass. One significant example of the prior art disclosures in this field is U.S. Pat. No. 3,704,137 which describes an essential oil composition formed by mixing an oil with an antioxidant, separately mixing water, sucrose and hydrolysed cereal solids with dextrose equivalent (DE) below 20, emulsifying the two mixtures together, extruding the resulting mixture in the form of rods into a solvent, removing the excess of solvent and finally adding an anti-caking agent. Another pertinent example is that described in U.S. Pat. Nos. 4,610,890 and 4,707,367 which disclose a process for forming a stable, melt based and extruded, solid, essential oil flavor composition, as well as a product of this process. The melt to be extruded consists, in this particular case, in a matrix formed of an aqueous mixture of a sugar and a starch hydrolysate together with a selected emulsifier, said aqueous mixture being further blended with a selected quantity of essential oil flavor. More recently, U.S. Pat. No. 6,707,771 has described a novel extrusion process wherein the extruded mass is chopped as it exits the die and when it is in a plastic state. This process avoids any drying step following extrusion. The above-mentioned patents are merely illustrative of the considerable volume of patent literature related to extrusion techniques.
Carrier materials described as being suitable for extrusion processes are also numerous. The most useful ingredients are long chain carbohydrates typically including starches, hydrogenated starch hydrolysates, modified starches and gums, in combination with or as alternative of low molecular weight carbohydrates such as mono- or disaccharides, maltodextrins having a dextrose equivalent (DE) in the range of about 4 to 20, and corn syrup solids or polydextrose having a dextrose equivalent in the range of about 21 to 97.
Now, the present invention relates to a novel encapsulating carrier composition essentially made of fibrous polysaccharides and more particularly made of soluble dietary fibres. Dietary fibres are commonly defined as polysaccharides which are resistant to the endogenous enzymes of man, i.e., that they are not digested by the endogenous secretions of the human digestive tract. They are divided into water-insoluble and water-soluble fibres. Water-soluble fibres have been widely described in the prior art because of their known health benefits, as ingredients used in food products, partly because they reduce the glycemic response to food and make thus food products which contain soluble fibres particularly suitable for diabetics. This prior art describes the use of water-soluble fibres as such in ready-to-consume products, but not as potential encapsulating materials.
On the other hand, soluble and insoluble fibres have also been disclosed as being potentially useful to be added in minor amounts to encapsulating compositions to control the release of the encapsulant (PCT publication WO 99/48372).
U.S. Pat. No. 6,468,568 discloses the encapsulation of a mineral such as calcium or a vitamin, in a double encapsulation system containing a fibre material. The active ingredient is firstly surrounded by an edible oil and then encapsulated in a glassy matrix composition including an oligosaccharide, which may be inulin. Inulin is a clean, dried fibrous material which is separated by extraction from, for example, chicory, onions or Jerusalem artichokes and other common plant sources. It is the only totally fibrous material mentioned in this document among other oligosaccharides. All the other oligosaccharide materials suitable for the purpose disclosed herein include sugars. The encapsulation method described in this document is extrusion and allows to obtain a product which is non-rubbery and readily grindable into fine particulate compositions or powders ready for incorporation into or onto food compositions. The glassy matrix compositions described can be extruded through extrusion dies having aperture diameters of from about 0.10 mm to about 5 mm. The diameter of the extrudate rope and product may be larger than the diameter of the die apertures due to deformation or swelling as the composition exits the die. The increase in diameter upon exiting the die may occur without substantial development of an expanded, puffed, foamy, or cellular structure.
According to the present invention, we have been able to realise a novel encapsulating carrier composition which, in addition to the fact that it consists essentially of fibrous materials and thus presents advantageous properties such as being sugar-free and non-cariogenic, enables the preparation of a particulate composition with a larger size than disclosed in the prior art, namely with a cross-sectional diameter of at least 3, preferably at least 5 mm and up to 15 mm. The products of the invention are therefore suitable either for direct consumption in applications in the sweet and savoury confectionary area and bakery area where they provide alternative products to known gelatine type candies, or small compressed tablets, or for an use as an efficient delivery system when added to an edible composition such as a foodstuff or beverage.